Search Results for Fe-0.8C

This article discusses the fracture and fatigue properties of powder metallurgy (P/M) materials depending on the microstructure. It describes the effects of porosity on the P/M processes relevant to fatigue and fracture resistance. The article details the factors determining fatigue and fracture resistance of P/M materials. It reviews the methods employed to improve fatigue and fracture resistance, including carbonitriding, surface strengthening and sealing treatments, shot-peening, case hardening, repressing and resintering, coining, sizing, and postsintering heat treatments. Safety factors for P/M materials are also detailed.

This article describes the benefits that can be achieved by using thermal spray on particular engine parts of an automobile. These include improvement in fuel consumption, wear resistance and bonding, and reduction of oil consumption, exhaust heat loss, and cooling heat loss. Typical engine parts are cylinder blocks, cylinder bores, cast iron cylinder liners, piston rings, connecting rod bearings, turbochargers, engine valve lifters, exhaust system parts, and oxygen sensors. The article also describes the benefits of using thermal spray on transmission parts such as synchronizer rings and torque converters.

This article provides information on the microstructure of powder metal alloys and the special handling requirements of porous materials. It covers selection, sectioning, mounting, grinding, and polishing, and describes procedures, such as washing, liquid removal, and impregnation, meant to preserve pore structures and keep them open for analysis. The article compares and contrasts the microstructures of nearly 50 powder metal alloys, using them to illustrate the effect of consolidation and compaction methods as well as particle size, composition, and shape. It discusses imaging equipment and techniques and provides data on etchants and etching procedures.

Precipitation reactions occur in many different alloy systems when one phase transforms into a mixed-phase system as a result of cooling from high temperatures. This article discusses the homogenous and heterogeneous nucleation and growth of coherent and semicoherent precipitates. It describes two precipitation modes, namely, general or continuous precipitation and cellular or discontinuous precipitation. The article also provides information on the precipitation sequences in aluminum alloys.

This article reviews the production variables that influence the selection of various stamping die materials: ferrous, nonferrous, and plastic die materials. It provides a discussion on the specific types of die materials for tool steels, cast irons, plastics, aluminum, bronze, zinc-aluminum, and steel-bonded carbides. The article describes factors to be considered during the selection of materials for press-forming dies.

Premanent magnet refers to solid materials that have sufficiently high resistance to demagnetizing fields and sufficiently high magnetic flux output to provide useful and stable magnetic fields. Permanent magnet materials include a variety of alloys, intermetallics, and ceramics. This article discusses the composition, properties, and applications of permanent magnetic materials, such as hysteresis alloys used in motors. It primarily focuses on the stability of magnetic fields that influences reversible and irreversible losses in magnetization with time, and the choice of magnet material, component shape and magnetic circuit arrangement.

Alloy phase diagrams are useful for the development, fabrication, design and control of heat treatment procedures that will produce the required mechanical, physical, and chemical properties of new alloys. They are also useful in solving problems that arise in their performance in commercial applications, thus improving product predictability. This article describes different equilibrium phase diagrams (unary, binary, and ternary) and microstructures, description terms, and general principles of reading alloy phase diagrams. Further, the article discusses plotting schemes; areas in a phase diagram; and the position and shapes of the points, lines, surfaces, and intersections, which are controlled by thermodynamic principles and properties of all phases that comprise the system. It also illustrates the application of the stated principles with suitable phase diagrams.

This article discusses the chief magnetic characteristics of permanent magnet materials. It provides a detailed description on nominal compositions; principal magnet designations; magnetic, physical, and mechanical properties; selection criteria; and applications of the permanent magnet materials, which include magnet steels, magnet alloys, alnico alloys, platinum-cobalt alloys, cobalt and rare-earth alloys, hard ferrites, iron-chromium-cobalt alloys, and neodymium-iron-boron alloys.

This article discusses the methods for producing powder metallurgy (PM) nickel powders, including carbonyl process, hydrometallurgical process, hydrogen reduction process, and atomization process, as well as their applications. It describes three processes for producing nickel alloy powders: water atomization, high-pressure water atomization, and gas atomization. The article also provides information on the applications of PM hot isostatic pressing in the oil and gas industry.

Certain metal products can be produced only by powder metallurgy; among these products are materials whose porosity is controlled. Successful production by powder metallurgy depends on the proper selection and control of process variables: powder characteristics; powder preparation; type of compacting press; design of compacting tools and dies; type of sintering furnace; composition of the sintering atmosphere; choice of production cycle, including sintering time and temperature; and secondary operations and heat treatment. When the application of a powder metallurgy part requires high levels of strength, toughness, or hardness, the mechanical properties can be improved or modified by infiltration, heat treatment, or a secondary mechanical forming operation such as cold re-pressing or powder forging. The article also discusses the effect of the secondary processes on P/M mechanical properties.

Three-dimensional microscopy can be used to reveal the shape, distribution, and connectivity of three-dimensional (3D) features that lie buried within an opaque material. This article discusses several experimental techniques that can be used to generate 3D images. These include serial sectioning, focused ion beam tomography, atom probe tomography, and X-ray microtomography. Nine case studies are presented that represent the work of the various research groups currently working on 3D microscopy using serial sectioning and illustrate the variants of the basic experimental techniques. The article also discusses the techniques for reconstruction and visualization of 3D microstructures with advanced computer software and hardware.